Wireless communication systems are known to comprise wireless communication units, such as in-car mobile and/or hand-held portable radios, that communicate with each other and a fixed infrastructure using wireless communication resources. Many of the user features provided by such wireless communication units are often based on software programs stored and executed within the wireless communication units. That is, algorithms electronically stored in memories are executed by processing devices, such as microprocessors, to realize certain features.
As existing features are improved and new features are developed for wireless communication units, new versions of software become available with increasing frequency. Users of wireless communication units typically desire to receive the newest versions of updated software as quickly and as efficiently as possible in order to take advantage of the improvements.
Prior art approaches for delivering updated software to wireless communication units are not always convenient and/or efficient. One method requires a user to bring the wireless communication unit to a central location, such as a service shop operated by a system administrator or service provider. The unit is then either provided with replacement parts containing the updated software (i.e., replacement memory devices) or physically connected to a device that transfers the updated software to the unit. Regardless of how the updated software is actually transferred, this method is both time-consuming and inconvenient to users since they are typically required to bring their unit in for service during normal work hours.
U.S. Pat. No. 5,689,825 to Averbuch et al. discloses an arrangement for downloading software from a server to a wireless terminal via a land-based public communication network using a battery charger/software downloader. According to Averbuch et al., downloading software via a land-based public communication network and a battery charger/software downloader has the advantage of minimizing inconvenience to the wireless telephone user. Averbuch et al. also asserts that downloading software via the land-based public communications network is advantageous over receiving updated software wirelessly as a special type of data message. According to Averbuch et al., software versions often comprise many megabytes of data, and thus require extensive use of wireless communication resources to send the updated software to a large number of units.
Digital cellular systems have evolved as a more efficient implementation of wireless communication systems over analog cellular systems. Digital cellular systems typically use time-division multiplexed access (TDMA) or code-division multiple access (CDMA) techniques. Digital cellular communication systems overcome the disadvantages in analog cellular systems, including noise susceptibility and limitations in spectrum efficiency. CDMA systems have been standardized according to TIA/EIA/IS-95A (“MOBILE STATION-BASE STATION COMPATIBILITY STANDARD FOR DUAL MODE WIDEBAND SPREAD SPECTRUM CELLULAR SYSTEM”—1995), by the Telecommunications Industry Association (“TIA”), the disclosure of which is incorporated in its entirety herein by reference.
With CDMA, each transmitted signal comprises a different pseudorandom binary sequence, also referred to as a pseudonoise (PN) sequence, that modulates a carrier signal, spreading the spectrum of the waveform. Thus, since each CDMA subscriber unit is assigned a unique PN code, a plurality of subscriber stations can send and receive CDMA signals sharing the same frequency spectrum. If these COMA signals were viewed in either the frequency or time domain, the multiple access signals would appear to be superimposed on top of each other. The CDMA signals are separated in the receivers of the base stations or the subscriber stations by using a correlator which accepts only signal energy from the selected binary PN sequence and despreads its spectrum. The CDMA signals from other sources, whose codes do not match the selected binary PN sequence, are not despread in bandwidth and as a result, contribute only to the background noise and represent a self-interference generated by the system. CDMA interference therefore can be controlled, with the goal of increasing system capacity, on the basis of the reduction in signal-to-noise ratio caused by other users within the cellular CDMA system. Thus, a goal in any CDMA system is to limit the power output of transmitters in order to minimize the cumulative system noise caused by the other users in the CDMA system.
The use of CDMA has also been proposed for Personal Communication Services (PCS). A proposed standard for a CDMA PCS system has been submitted by the Joint Technical Committee of the TIA, entitled PN-3384, “PERSONAL STATION-BASE STATION COMPATIBILITY REQUIREMENTS FOR 1.8 TO 2.0 GHz CODE DIVISION MULTIPLE ACCESS (CDMA) PERSONAL COMMUNICATIONS SYSTEMS”, Nov. 3, 1994, the disclosure of which is incorporated herein by reference. The PCS proposed standard PN-3384 specifies enhanced services including transmission rates up to 14.4 kbps for enhanced speech quality, full data services at rates up to about 13 kbps, and simultaneous transmission of voice and data. The CDMA PCS system is adapted to operate in any of the licensed PCS frequency allocations from the FCC, currently assigned at 1930-1990 MHz band for the forward CDMA channel (base station to subscriber), and 1850-1910 MHz for the reverse CDMA channel (subscriber to base station).
Data service capabilities for an IS-95A system are specified in TIA/EIA/IS-99 (“DATA SERVICES OPTION STANDARD FOR WIDEBAND SPREAD SPECTRU DIGITAL CELLULAR SYSTEMS”—1995), and TIA/ELA/IS-707 (“DATA SERVICE OPTIONS FOR WIDEBAND SPREAD SPECTRUM SYSTEMS”—1997), incorporated in their entirety herein by reference. These standards specify a circuit switched wireless data protocol used by CDMA cellular mobile stations and base stations to provide modem emulation over the CDMA digital cellular telephone. These standards also define procedures for the interface between the base station and mobile switching center (BS/MSC), and an Interworking Function (IWF) that converts the data from the wireless data protocol to a format compatible for the public switched telephone network (PSTN).
Hence, digital telephones can serve as wireless modems that send and receive wireless data packets for portable laptop PCs, where the wireless data packets are sent and received by the digital telephones according to a wireless data protocol such as IS-99 or IS-707. In this case, data frames from the laptop PC are output as wireless data packets by the digital wireless telephone to the wireless digital communications system, and wireless data packets received by the digital wireless telephone from the wireless digital communications system are output by the digital telephone to the laptop PC.
Hence, a customer can connect his or her portable laptop PC to the digital CDMA telephone using an RS-232 cable, and configure the dial-up software resident in the laptop PC to set up the laptop PC to send and receive faxes via the digital wireless telephone in the form of wireless data packets. In addition, a user of a laptop PC may use the digital CDMA phone as a wireless modem to dial into an Internet Service Provider (ISP), or a corporate local area network (LAN) to access Internet or intranet services. The digital cellular or PCS system, upon receiving the wireless data call, connects the call to an Interworking Function (IWF) unit, which performs the necessary tasks to process data and fax transmissions into circuit-switched data and digital fax connections via the public switched telephone network. Hence, a user can browse the Internet or send a fax with the laptop PC using the wireless data connection.
The above-described wireless data protocols, however, contemplate use of the digital telephone as a wireless modem for a mobile computer such as a laptop PC, and do not address the problem of downloading upgraded software directly into the digital telephone. In addition, the standards specify only the protocol of the packet data transmitted via the air interface. Hence, transmission and reception of wireless data is typically performed by executing proprietary call processing software embedded in the digital telephone or the IWF unit. The use of proprietary call processing software limits the flexibility of potential application developers in developing improved software for use by the wireless telephones. Moreover, the use of proprietary call processing software in the digital telephone and the IWF unit requires the digital wireless telephone service providers to rely on the vendors of the proprietary software to maintain the digital wireless telephone infrastructure. For example, a proposed standard TIA/EIA/IS-683 specifies an over-the-air voice service activation procedure by placing a voice call on a CDMA and/or analog voice channel. The implementation of new digital wireless telephone services such as over-the-air activation as specified in IS-683 requires modification of the proprietary software in the infrastructure components, including the digital telephones, the mobile switching center, and the IWF, resulting in increased costs and delays in implementing new digital wireless telephone services.